Field of the Invention
The present invention relates to an angular velocity sensor and a manufacturing method thereof, and in particular to an angular velocity sensor of a vibration gyro type having a structure in which a weight is supported by a piezoelectric diaphragm, and a manufacturing technique thereof.
Description of the Related Art
A MEMS (Micro Electro Mechanical System) vibrating gyrosensor using a silicon (Si) fine-processing technique has features such as being small in size and of low power consumption and various applications thereof including especially mobile applications and the like are expected. A typical MEMS vibrating gyrosensor takes a structure in which a portion serving as a weight is supported by a vibration spring, so that the gyrosensor causes the weight to vibrate by a driving force and detects a Coriolis force that occurs when an angular velocity is externally applied, and thereby performs angular velocity detection (see Japanese Patent Application Laid-Open No. 2010-160095 (PTL 1) and Japanese Patent No. 4012232 (PTL 2)).
For example, an angular velocity sensor proposed in PTL 1 has a structure in which a weight is supported by a piezoelectric diaphragm, and is configured to cause the weight to make resonance vibration driving by directing the weight in a vertical (z-resonance driving) direction and a horizontal (x-resonance driving) direction, and thereby detects an angular velocity. In addition, an angular velocity sensor proposed in PTL 2 detects an angular velocity of three axes (x-axis, y-axis, and z-axis) by causing a weight (heavy weight body) to make circulating movement along a circulation orbit. This structure is small-sized and has an advantage of being capable of detecting angular velocities about all of the three axes.